Grinding machine



- Aug. 21, 1956 H. A. slLvEN ETAL .2,759,304

` GRINDING MACHINE Filed Jan. 50, 1956 7 Sheets-Sheet l www A TToE/VEYAug. 2l, 1956 H. A. SILVEN `EVAL GRINDING MACHINE 7 Sheet's-Sheet 2Filed Jan. 30, 1956 lNvl-:N'roRs HERBERT A. SILVEN STEWART 5'. MAJJERATTRNEY Aug. 21, 1956 H. A. slLvEN ETAL 2,759,304

GRINDING MACHINE Filed Jan. so, 195e A 7 sheets-sheet s INVENToRsHERBERT A. 51m/EN STEWART 5. MAJUER H. A. SILVEN ETAL Aug. 21, 1956GRINDING MACHINE 7 Sheets-Sheet 4 Filed Jan. 30, 1956 QQN mw A QN4 A s TY @MTM H x B Y m w l m. r r

mvENToRs HERBERT A. .Ew/ VEN STEWART S. MAJJER ATTCRNEY -Aug.21,1956HASILvi-:N Em 2,759,304

GRINDING4 MACHINE i Filed Jan. 30, 1.956 l A7 Sheets-Sheet 5 IN EN'roRsHERBERT A. 51m/EN STEWART S. MAIIER ATTDRNEY Aug. 21, 1956 H. A. slLvENETAL 2,759,304

GRINDING MACHINE:

Filled Jan, 30, 1956.

7 Sheets-Sheet 6 INVENTOR HERBERT A6 5/L VEN 5 TEWAR'T 5. MADER' Aug.21, 1956 H. A. slLvEN rs1-AL GRINDIING MACHINE Filed Jan. 3o, 195s 7Shee'cs-Sheevl 7 /04 l HERBERT A.

INVENTORS 5/L VEN Erg/(MRT 5. Afl/mila Wm.rnn

A -r Toe/VEY United States Patent() M GRINDING MACHINE Herbert A.Silven, West Boylston, and Stewart S. Mader, Worcester, Mass., assignorsto Norton Company, Worcester, Mass., a corporation of MassachusettsApplication January 30, 1956, Serial No. 562,251

6 Claims. (Cl. 51-165) The invention relates to grinding machines andmore particularly to a grinding wheel feeding mechanism which isarranged to precisely and automatically control work size.

One object of the invention is to provide a simple and thoroughlypractical feeding mechanism for precisely feeding a grinding Wheel so asto control work size. Another' object of the invention is to provide afeeding mechanism combined with an automatic wheel truing mechanism anda feed compensating mechanism automatically to compensate for wheel Wearcaused by grinding and truing. Another object of the invention is toprovide a feed cornpensating mechanism which is arranged automaticallyto true the grinding whel and to compensate for wheel wear after apredetermined number of work pieces have been ground. Another object ofthe invention is to provide a feed compensating mechanism which operatesautomatically in timed relation with the wheel slide movement tocompensate for wheel wear which is arranged automatically to omitcompensation in case of wear on the truing tool. Other objects will bein part obvious or in part pointed out hereinafter.

In the accompanying drawings, in which isshown one of various possibleembodiments of the mechanical features of this invention,

Fig. l is a fragmentary vertical sectional view through a grindingmachine showing a portion of the wheel feeding mechanism; t

Fig. 2 is a fragmentary front elevation of the grinding wheel feedingmechanism;

Fig. 3 is a vertical sectional view, taken approximately on the line 3-3of Fig. 2, through a portion of the wheel feeding mechanism; l

Fig. 4 is a fragmentary sectional view, on an enlarged scale, takenapproximately on the line 4-4 of Fig. l, through feed compensatingmechanism;

Fig. 5 is a fragmentary side elevation of a portion of a grindingmachine, showing the feed compensating mechanism;

Fig. 6 is a combined electric and hydraulic diagram of the actuatingmechanisms including the wheel truing apparatus and the feed compensatorand the controls therefor; and Y Fig. 7 is a combined hydraulic fandelectrical diagram of the wheel feeding mechanism together with the worksizing gauge and the controls therefor.

A lgrinding machine has been illustrated in the drawings comprising abase 10 which supports a wheel slide base 11 (Fig. 4). The wheel slidebase 11 in turn supports a transversely movable wheel slide 12 which isarranged to slide transversely relative to the base 10 and the wheelslide base 11 on a V-way 13 and a fiatway (not shown) formed on theupper surface of the wheel slide base 11. The wheel slide 12 serves as asupport for a rotatable wheel spindle 14 which is journalled in suitablebearings (not shown). The wheel spindle 14 supports a `grinding wheel 15(Fig. l) which may be driven in the conventional 2,759,304 Patented Aug.21, 1956 ICC manner by means of an electric motor 16 (Fig. 5) mounted onthe upper surface of the wheel slide 12.

A feeding mechanism is provided for the wheel slide 11 comprising arotatable feed screw 20 having a reduced cylindrical portion 21 which isslidably keyed within a rotatable sleeve 22. The sleeve 22 is journalledin spaced anti-friction bearings 23 and 24 (Fig. l) which are iixedlysupported by the wheel slide base 11. The other end of the feed screw 20is supported by anti-friction bearings 25 which are carried by aslidably mounted sleeve 26 which slides within a cylindrical bore 27formed in the wheel slide base 11.

A rotatable feed nut 28 is journalled ina pair of spaced anti-frictionbearings 29 and 30 which are carried by a bracket 31 depending from theunderside of the wheel slide 12.

A hydraulically operated mechanism is provided for causing a rapidapproaching and receding movement of the wheel slide 11 for moving thegrinding wheel to and from an operative position. This mechanism maycomprise a cylinder 35 which is arranged in axial alignment with thefeed screw 20 and the sleeve 26. The cylinder 35 contains a slidablymounted piston 36. A piston rod 37 is connected at one end to the piston36 and at the other end to the sleeve 26 so that when fluid underpressure is `admitted to either one end or the other of the cylinder 35an axially feeding movement will be imparted to the feed screw to causea transverse movement of the wheel slide 12 and the grinding wheel 15.

A feed control valve 40 is provided for controlling the admission to andexhaust of fluid from the cylinder 35. The valve 4t) is preferably apiston-type valve comprising a valve stem 41 having a plurality of valvepistons 42, 43 and 44 formed integrally therewith to form a pair ofspaced valve chambers 45 and 46. A compression spring 47 serves normallyto maintain the valve stem 41 in its right hand end position asillustrated in Fig. 7. A solenoid S3 is operatively connected to theright hand end of the valve stem 41 and is arranged so that whenenergized it shifts the valve stem 41 toward the left into a reverseposition.

A fluid pressure system is provided for supplying Huid under pressure tothe operating mechanisms of the machine comprising a motor driven fluidpump 48 which draws fluid through a pipe 49 from a reservoir 50 andforces uid under pressure through a pipe 51 to the various operatingmechanisms of the machine including the feed control valve 40. Apressure relief valve 52 is connected to the pipe 51 by means of whichexcess uid under pressure may be by-passed directly through a pipe 53into the reservoir 50 to facilitate maintaining a substantially uniformoperating pressure in the hydraulic system.

In the position of the valve 4@ (Fig. 7) fluid under pressure passingthrough the pipe 51 enters the valve ch amber 45 and passes through apassage 54 into a cylinder chamber 55 to cause the piston 36 to movetoward the right into an inoperative position as illustrated in Fig. 7.Movement of the piston 36 toward the right also imparts a correspondingmovement to the feed screw 2u, the feed nut 28, the wheel slide 12 so asto move the grinding wheel 15 to a rearward or inoperative position.During this movement of the piston 36, fluid within a cylinder chamber56 may exhaust through a passage S7, through the valve chamber 46 andpasses out through an exhaust pipe 58 into the reservoir 50.

In order to slow down the rapid rearward movement of the piston 36, adashpot mechanism 3S is provided which is actuated by the right hand endof the piston rod 37 in a manner substantially the same as that shown inthe U. S. patent to H. L. Swainey No. 2,582,610 dated Janin ary l5,1952, -to which reference may be had for details of disclosure notcontained herein.

A feed apron 60 is mounted on the front of the machine base 10. Thisapron supports a rotatable manually operable feed wheel 61 which isprovided with the usual micrometer adjusting mechanism 62. The feedWheel 61 is connected through the micrometer adjusting mechanism with agear 63. Both the feeding wheel 61 and the gear 63 are rotatablysupported on a fixed shaft 64, A gear 65 is formed integrally with thegear 63 and meshes with a gear 66 rotatably supported on a shaft 67. Thegear 66 meshes with a gear 63 which is tixedly mounted on a rotatableshaft 69. The shaft 69 is journalled in spaced anti-friction bearings 70and 71 which are iixedly mounted Within the feed apron 60. A gear 72 isxedly mounted on the other end of the shaft 69 and meshes with a gear 73which is supported by a pair of spaced anti-friction bearings 74 and 75which are in turn supported by the feed apron 60. A rotatable shaft 76is slidably keyed within a central aperture formed in the gear 73. Theother end of the shaft 76 is slidably keyed within a rotatable sleeve 77which is supported in spaced anti-friction f bearings 78 and 79 carriedby the wheel slide base 11. A gear 80 is formed integral with the sleeve77 and meshes with a gear 81 formed integral with the sleeve 22. It willbe readily apparent from the foregoing disclosure that a rotary motionof the feed wheel 61 will be transmitted through the gear mechanism justdescribed to impart a rotary motion to the feed screw 20 which in turncauses a transverse feeding movement of the Wheel slide 12 and thegrinding Wheel 15.

A feed pawl 85 is pivotally mounted on a stud 86 on the front of themachine base. The upper end of the feed pawl 85 is provided with a camface 87 which is arranged to be engaged by a cam 88 adjustably supportedon the feed wheel 61. The feed pawl 85 is provided with an integraldownwardly extending arm 89'. A tension spring 90 is connected at oneend to a bracket 91 and at the other end to a stud 92 to exert a tensiontending to rock the feed pawl 85 into engagement with an adjustable stopscrew 93.

The cylinder 35 and piston 36 previously described serve to cause arapid approaching movement of the Wheel slide 12 to position thegrinding wheel 15 into an operative position relative to the work pieceto `be ground.` In order to feed the grinding wheel 15 during a grindingope-ration a fluid operated mechanism is provided to impart a rotarymotion to the feed screw 20. This mechanism may cornprise a cylinder 99which contains a slidably mounted piston 100. The piston 100 is providedwith rack'teeth 101 which mesh with a gear 102 carried by a shaft 103.The shaft 103 is provided with a gear 104 which meshes with the gear 68.It will be readily apparent from the foregoing disclosure that alongitudinal movement of the feed piston 100 will be imparted throughthe gear mechanism above described, to impart a rotary feeding movementto the feed screw 20. This feeding mechanism may be substantiallyidentical with that shown in the U. S. patent to Homer L. Swainey No.2,5 82,610 dated January 15, 1952, to which reference may be had fordetails of disclosure not contained herein.

An automatic control mechanism is provided for automatically controllinglthe duration of the ,grinding cycle comprising a work gauging head 110which is provided with a slidably mounted work contact member 111 whichis arranged to engage the peripheral surface cf a Work piece 112 beingground. The gauging head 110 is provided with a C-shaped caliper head113 having a pair of adjustably mounted work engaging screws 1,14 and115 to facilitate maintaining the gauging head 110 in a predeterminedrelationship with the axis of the work piece 112 during a grindingoperation. The gauging head 110 is preferably supported by a bracket(not shown) on. the wheel slide 12. This type of mounting is a'n old andwell known expedient in the art and therefore has not been illustratedin the present application.

The upper end of the Work contact member 1'1-1, engages a rock arm 116which is pivotally mounted on a stud 11.7. A compression spring 11S isarranged to exert a downward pressure on the rock arm 116 so as tomaintain the contact member 111 in operative engagement with theperiphery of the work piece 112 during the grinding operation. The rockarm 116 is provided with an electrical contact member 119 which isarranged to move into engagement with the contact member 120 within thegauging head 110. An adjustment screw 121 is provided for adjusting thecontact member 120 to facilitate setting up the gauge for sizing so asto grind a work piece to a predetermined size.

A pair of power lines L1 and L2 serve to supply electrical power tooperate the various mechanisms of the machine. A manually operablecontrol lever 124 is pivotally mounted on a stud 125 which is in turnsupported on the front of the machine base 10. The control lever 124 isarranged to close a normally open start switch 126 when the lever 124 isrocked in a counter-clockwise direction and to open a normally closedstop switch 127 when rocked in a clockwise direction. CR7 and a relayswitch CR6 together with a selector switch 130 are provided forcontrolling the feeding mechanism in a manner to be hereinafterdescribed.

When it is desired to start a grinding cycle, the control lever 124 isrocked in a counter-clockwise direction to close the start switch 126which serves to energize the relay switch CR7 to close a circuit andthereby to energize the solenoid S3 to shift the feed control valve 40toward the left (Fig. 7) to start a forward approaching and feedingmovement of the wheel slide 12 and the grinding wheel 15. The relayswitch CR7 is provided with a holding circuit so that only a momentaryclosing of the start switch 126 is required to start the grinding cycle.The piston 36 moves toward the left (Figs. l and 7) to cause a rapidapproaching movement of the wheel slide 12 and the grinding wheel 15.The rapid approaching movement continues until the piston 36 engages theleft hand end of the cylinder 35 after which the approaching movement ofthe wheel slide 12 is reduced to a grinding feed as governed by themovement of the feed piston 100 toward the right (Fig. 2).

The grinding feed continues until the work piece 112 has been ground toa predetermined size at which time the member 111 moves downwardly sothat movement of the rock arm 116 in a clockwise direction moves thecontact member 119 into engagement with the contact member 120 to closea circuit thereby energizing relay switch CR6 to open the contactsthereof thereby breaking a circuit to deenergize the solenoid S3V sothatv the released compression of the spring 47 shifts the feed controlvalve 40 toward the right into the position illustrated in Fig. 7. Inthis position of the valve 40,. uid under pressure passes through thepassage 54 into the cylinder chamber 55 to move the piston 36 toward thcright into an inoperative position as illustrated in Fig. 7.

A shuttle-type control4 valve 135 is provided` for controlling theadmission to. and exhaust of uid from the cylinder 99. The valvecomprises a slidably mounted valver member having a plurality of spacedvalve pistons 136, 137 and 138 forming a pair of valve chambers 139 andv140. A compression spring 141 is provided normally to hold the valve 135in a left handv end position, as shown in Fig, 7. In order to shift thevalve 135 into a right hand end position, the pipe 51 is connected by amanually operable valve 142. with av pipe 143 whichl in turn isconnected to a left handy end chamber 144 within the valve 135. Whenitis desired to shift the valve 135 into` a right hand end position, thevalve 142 may be opened to admit uid under pressure from the pump 48,through the pipe 51y into the end chamber 144 to shift the valve-intola' right hand end position in which position uid mayby-pass from one endof the cylinder 99 to the other.

A pair of pipes 145 and' 146 are connected between the A relay switchfeed control valve and the shuttle type valve 135. Similarly a pair ofpipes 147 and 148 are connected between the shuttle valve and a pair ofend chambers 149 and respectively formed within the cylinder 99. In theposition of the feed control valve 40 and the shuttle type valve 135(fig. 7) fluid under pressure from the pressure pipes 51 entering thevalve chamber 45 passes through the pipe 145, through the valve chamber140, through the pipe 148 into the cylinder chamber 150 to move thepiston 101i toward the left into the position illustrated in Fig. 7.During this movement uid within the cylinder chamber 149 may exhaustthrough the pipe 147, through the valve chamber 139, through the pipe146 into the valve chamber 46 and exhausts through the exhaust pipe 58.

When the solenoid S3 is energized at the start of a grinding cycle toshift the valve 40 to its left hand end position uid under pressure fromthe pipe 51 passes into the valve chamber i6 and through the passage 57into the cylinder chamber 56 to start a rapid movement of the piston 36toward the left rapidly to move the wheel slide 12 and the grindingwheel 15 into an operative position. At the same time fluid underpressure entering the valve chamber t6 passes through the pipe 146,through the valve chamber' 139, through the pipe 147 into the cylinderchamber 169 to start the piston 100 moving toward the right (Fig. 7) toproduce a slow rotary motion of the feed screw 28 to impart a grindingfeed to the wheel slide 12 and the grinding wheel 15.

A feed compensating mechanism is provided automaticaliy to compensatefor wheel truing and wheel Wear comprising a cylinder (Figs. 5 and 6)which contains slirlably mounted piston 156. The piston 156 is connectedto the right hand end of a piston rod 157. A compression sprirs0 servesnormally to hold the piston 156 in a right hand end position in thecylinder U 155. When duid under pressure is passed through a passage1559 into a cylinder chamber 160 (Fig. 6) the piston 156 will be movedtoward the left.

A control valve 161 is provided for controlling the admission to andexhaust of uid from the cylinder 155. The valve 161 is preferably apiston type valve comprising a valve stem 162 having a pair of spacedvalve pistons formed integrally therewith so as to form a valve chamber163.

passage 159, through the valve chamber 163 and exhausts through a pipe164. A compression spring 165 serves normally to hold the valve stem 162in a right hand end position. A solenoid S2 is provided which whenenergized serves to shift the valve stem 162 toward the left. Thesolenoid armature is connected by a stud 166 with a link 167. The otherend of the link 167 is connected by a stud 166 with the lower end of arock arm 169. The rock arm 169 is pivotally supported by a stud 170carried by a bracket 1/ 1. The upper end of the rock arm 169 is providedwith an elongated slot 172. A stud 173 fixedly mounted on the left handend of the valve stem 162 rides within the slot 172. It will be readilyapparent from the foregoing disciosure that when the solenoid S2 isenergized, the valve stem 162 moves toward the left so that iuid underpressure from the pressure pipe 51 passes through the valve chamber 163,through the passage 159, into the cylinder chamber 160 to move thepiston 156 toward the left (Fig. 6).

The left hand end of the piston rod 157 is provided with a stud 175which is connected to one end of a link 176. The other i of the iink 176is connected by a stud 177 with a vertically arranged arm 178 of a bellcrank pawl carrying lever which is rotatably supported on a shaft 179.The bell crank lever is provided with a second arm 155i) which isarranged in the path of a pair of adiustable stop screws 181 and 182carried by a fixed bracket 183. The arm 178 is provided with a feed pawl184 which is pivotally connected thereto by a stud 185. The pawl 184 isarranged to engage the teeth of ratchet in the position of the valve 161(Fig. 6) fluid may exhaust from the cylinder chamber 160, through thefacilitate holding the ratchet wheel 186 against clockwise movementduring operation of the pawl 184. The ratchet wheel 186 is keyed ontothe rotatable shaft 179 which is journalied in spaced anti-frictionbearings 190 and 191 4supported within the wheel slide 12. A gear 192 iskeyed to the left hand end of the shaft 179 (Fig. 4) and meshes with agear 193 rotatably supported on a xed stud 194. The gear 193 meshes witha gear 195 keyed onto a rotatable worm shaft 196. The worm shaft 196 isrotatably supported in spaced anti-friction bearings 197 and 198 carriedby the downwardly projecting bracket 31 mounted on the underside of thewheel slide 12. The worml shaft 196 is provided with a worm 199 which iskeyed thereon and meshes with a worm gear 200 formed integrally with theperiphery of the feed nut 28. It will be readily apparent from theforegoing disclosure that actuation of the ratchet Wheel 186 by the pawl184 will be imparted through the gear mechanism above described toimpart a rotary motion to the feed nut 26 so as to compensate forgrinding wheel wear due to truing operations and normal wheel wearduring grinding. The amount of compensation may be regulated byadjustment of the stop screws 181 and 182. These stop screws areadjusted so as to impart a compensating feed equal to the feed of thetruing tool at each end of its stroke.

A wheel guard-type truing apparatus is provided comprising a frame 265which is tlxedly mounted on the wheel slide 12. The frame 265 supports alongitudinally movable slide 206 which carries a transversely movabletruing tool carrier 267 having a diamond or truing tool 208 fixed at itslower end (Fig. 6). A forming bar 209 is fixedly mounted relative to theframe 205 and in the present case is provided with a plane operativeface which is engaged by a follower 216 carried by the truing toolcarrier 207.

A hydraulically operated mechanism is provided for traversing the truingtool 263 longitudinally so as to traverse it across the peripheral faceof the grinding Wheel 15. This mechanism may comprise a cylinder 211which is iixedly mounted relative to the frame 205. The cylinder 211contains a slidably mounted piston 212 which is connected to the lefthand end of a piston rod 213 (Fig. 6). The right hand end of the pistonrod 213 is connected to an upwardly extending bracket 214 fixedlymounted on the longitudinally movable slide 2116. When lluid underpressure is passed through a pipe 215 into a cylinder chamber 216, thepiston 212 together with the slide 206 is traversed toward the right(Fig. 6). During this movement, fluid within a cylinder chamber 217 mayexhaust through a pipe 218. The slide 206 is provided with an upwardlyextending lug 219 which is arranged in the path of a normally closedlimit switch L84, the function of which will be described hereinafter.

A control valve 221) is provided for controlling the admission to andexhaust of uid from the cylinder 211. The control valve 2211 comprises aslidably mounted valve member 221 which is controlled by a pilot valve222. The pilot valve 222 is normally held in a right hand end positionby means of a compression spring 223. A solenoid S1 is provided whichwhen energized serves to shift the pilot valve 222 into a left hand endposition.

ln the position of the valves 22% and 222 (Fig. 6), fluid under pressurefrom the pipe 51 enters a valve chamber 224 in the valve 220 and passesout through the pipe 218 into the cylinder chamber 217 to move thepiston 212 and the longitudinally movable slide 2&6 toward the left.During this movement fluid may exhaust from the cylinder chamber 216,through the pipe 215 into the valve chamber 225, through a centralpassage 226 in the s1id ably mounted valve member 221, into a valvechamber 227 and exhausts through a pipe 228 and a throttle valve 229. Bymanipulation of the throttle valve 229, the rate of movement of thepiston 212 and the slide 206 may be readily controlled as desired. Fluidunder pressure entering the valve chamber 224 in th'e valve 220 als'opasses through 'a passage' into 'a valve chamber 230 in 'the pilot Valve222, through a 'passage 231 into an end chamber 232 lto move theslidably mounted valve 'member 221 toward the left into a `left hand endposition, a's illustrated in Fig. 6, and to hold it in this position.During this movement of the valve member 221 uid within an end chamber233 may exhaust through a passage 234 into a valve chamber 235 in thepilot valve 222, 'through aeentral vpassage in the pilot valve 222 intoa valve chamber 236 and passes out throughan exhaust pipe 237.

When the solenoid S1 is energized, the pilot valve 222 is ishifted toits left hand end position sov that fluid under pressure from the valvechamber 224 in the valve y220 passes into the valve chamber 233 to shiftthe slidably mounted valve member 221 toward the right thereby reversingthe bwof'iluid to the cylinder 211 so ais to cause the piston 212together with the slide 206 to move toward 'the' right therebytraversing the truing tool 208 in the reverse direction across theoperative face of the grinding Wheel 15. 'Before ea'ch pass of thetruing tool across the Aoperative face of the grinding wheel 15, apredetermined 'down 'feeding movement is imparted to the truing tool208. This truing tool feeding mechanism has not been illustrated in thepresent case, since this truing apparatus is identical with that shownin the prior U. S. patent to Oiva AE. Hill NO. 2,659,359 dated November17, 1953, 'to which'reference may be had for vdetails of disclosure notcontained herein.

The slidably mounted sleeve 26 supports a bracket 240. A rod 241 isfixedly mounted to the bracket 240 and serves to actuate a pair of limitswitches LS1 and LS?. (Fig. 1) dii'ring the transverse movement of thewheel slide 11. As shown in Fig. l the wheel slide 12 is in a rearwardposition. When the wheel slide moves forward, that is, toward the left(Fig. l), the rod 41 rides olf the'actuating 'roller ofthe limit switchLS1 to allow the limit switch to open; After further forward movemento'f the wheel slide 12, the rod 241 rides off the limit switch LS2 andallows the switch `LS2 to close.

Referring now to Fig. 6*, the closing of switch SW1 serves through theno'w held close limit switch LS1 to energize a relay switch CR1 to openthe normally/'closed contacts 245 and to close the normally opencontacts 246. The closing ofthe contacts 246 serves to energize anelectric counter T1. The energizing of the timer T1 closes the contacts247 which establishes a holding circuit to maintain the counter T1energized. The energizing of the counter T1 also opens contacts 248which remain open` until count-out.

During aninfeeding movement of the wheel slide 12 the rod 241 (Fig. l)rides -oif the limit switch LS1 to allow vthe limit switch LS1 to openbreaking a circuit to deenergize the relay switch CR1 'so that thenormally closed contacts '245 are'again closed. As the wheel slide con-'tinues its forward movement, rotation of the feed wheel '61 moves thecam 88 into engagement with the cam 87 to 'rock the`pawl 85 andthe arm89 in a counterclockwise direction Vthereby allowing the limit switchLS3 to close. The closing ofithe li'mit switch LS3 energizes relayswitch 'CRZ .to close contacts 249 which make a circuit through the nowclosed contacts 245 of the relay switch CR1to energizerel'ay switch CRS.The energizing of relay switch The relay'swit'ch CR3'is normallyenergized during each forward movement of the `wheel slide providingthere has 'been no wearon the truing tool. In case of Awear on the'truing to'ol,'as willgbe hereinafter described, the cam '88will-notmovea suilicient-distanceto engage the car`r187 and to actuatethe limit switch LS3.

During each forward movement lof the wheel slide the limit switch L82 isclosed to impart a counting impulse to 'the counter T1. A'fter apredetermined number of work pieces have been ground according to thesetting of the connter T1, the rearward movement of the wheel slideopens the limit switch LS2 which serves to break the holding circuit tothe counter T1 which serves to deenergize the counter and allow it toreset for the next cycle. The closing of the contacts 248 completes acircuit through the selector switch SW4 and through the contacts 251 ofthe relay switch CR3 to energize the relay switch CRS. Unless vthere hasbeen truing tool wear, the 'limit switch LS3 is closed on the lastground work piece which completes the circuit 'through the contacts 251.When the relay switch CRS is energized, the contacts 252 are closed toenergize the solenoid S2 to start a compensating feed to compensate forwheel wear and truing. At the same time the contacts 248 close, atcount-out, a circuit is closed through the normally closed limit switchlLSi to energize `a relay switch CR4. Energizing relay switch CR4 closesa pair of contacts 253 to set up a Iholding circuit to maintain therelay switch CR4 energized. The energizing of relay switch CR4 serves toclose a second pair of contacts 254 to complete a circuit toien'ergizethe solenoid S1 to start a truing cycle, that is, one completereciprocation of the truing tool 208 across the operative -face of the'grinding wheel 15. The energizing of solenoid S1 starts movement of thetruing tool 208 toward the right to make the lirst pass of the truingtool across the face of the wheel 15. When the bracket 2I9=engages theactuating plunger of limit switch LS4 to open ya Vcircuit to vbreak theholding circuit to deenergize the relay :switch CR4 thereby opening thecontacts 254 to -deenergize the solenoid S1 thereby reversing the flowof fluid tothe cylinder 211 to start a traversing movement of the truingtool 208 toward the left. As previously explained the Atruing tool 208is fed downwardly at each end of the stroke as disclosed in the prior U.S. patent lto O. E. Hill No. 2,659,359, above referred to.

yNow referring to Fig. 7, when it is desired to start a .grinding cycle,the work gauge is moved into engagement with the work piece to be groundafter which the Vcontrol lever '124-is rocked in a counter-clockwisedirection to close the start switch 126 which serves in a mannerpreviously described to energize the solenoid S3 to shift the feedcontrol valve 40 toward the left tfhereby feed of the wheel slide 12.yWhen the work piece has been ground to a predetermined size, thecontact 119 engages the contact to close a circuit to energize the-relay switch'CR6 therebybreaking the circuit to deener- `gize thesolenoid S3 which reverses the direction of now of tluid to thecylinders 35 and 99 respectively to cause 'afrearward movement of thewheelslide 12 and a rotary -motion ofthe feed screw 20 in the reversedirection to reset th'efeed mechanism for the next grinding cycle.

"Unlessith'e truing tool has worn, the cam 88 on the feed wheel 61 willactuate the pawl arm 85 to close the limit switch LS3 aftereaoh workpiece has been ground. If the truing tool 208 has worn away, thegrinding wheel 15"will be slightly larger in diameter and therefore thework sizing gauge 110 will reverse the direction of movement lof thewheel slide before the cam 88 moves into engagement with the cam 87 sothat the switch LS3 will 'not be lclosed s'o that at count-out tlhecompensator will not operate but-'the truing apparatus is renderedoperat'ive' to 't'ru'e thep'e'ripheral face of the grinding wheel.

`The* operation `of the improved grinding machine will'b'ereadilyapparentfrom the foregoing disclosure. As-

suming all of the adjustments have been previously made, a work piece112 is positioned in the machine, the gauge head 110 is moved intooperative engagement with the Work piece 112. The main switch SW1 (Fig.6) is then closed to render the electric circuits operative. The startlever 124 is then rocked in a counter-clockwise direction to close thestart switch 126 thereby energizing the solenoid S3 to start a forwardfeeding movement of the wheel slide 12 and grinding Wheel 15. Theinfeeding movement continues until the work piece has been ground to apredetermined size at which time the contacts 119-12@ close todeenergize the solenoid S3 thereby causing a rapid rearward movement ofthe wheel slide 12 :and grinding wheel 15 to an inoperative position.Movement of the wheel slide serves in a manner previously described toenergize the count coils of the electric counter T1 so that after apredetermined number of work pieces have been ground, the solenoid S2 isenergized to impart Ia compensating feed adjustment, that is, a rotarymotion of the feed nut 2S to compensate for the 'amount of truing andWheel Wear. At the same time solenoid S1 is energized to initiate atruing cycle. The truing tool 208 is passed through one completereciprocation across the peripheral face of the grinding wheel 15 totrue the wheel to the desired yand predetermined extent.

The compensating feed occurs after count-out, unless the truing tool2tl8 has worn. In case the truing tool has worn, the diameter of thegrinding wheel 15 will be oversized so that when the work piece has beenground to a pretermined size, the gauge head 110 will cause a rapidseparating movement of the wheel to an inoperative position before thecam 88 engages the cam 87 to actuate the limit switch LS3. In thislatter case no compensating feed adjustment is made and the truing cycleserves to reduce the diameter of the wheel. Unless the cam 88 rotates ina counter-clockwise direction a suflicient distance to engage the cam S7and to rock the pawl arm 85 so as to actuate the limit switch L83, nocompensating feed adjustment will be made.

It will thus be seen that there has been provided by this invention agrinding machine in which the various objects hereinabove set forthtogether with many thoroughly practical advantages are successfullyachieved. As many possible embodiments may be made of the aboveinvention and as many changes might be made in the embodiment above setfortlh, it is to be understood that all matter hereinabove set forth orshown in the accompanying drawings is to be interpreted as illustrativeand not in a limiting sense.

We claim:

l. In a grinding machine having a base, a transversely movable wheelslide thereon, a rotatable grinding wheel thereon, means including a nutand screw mechanism to feed slide transversely in either direction,means including a motor to rotate said screw so as to impart a grindingfeed to said slide, a feed compensator operatively connected to impart arotary motion to said feed nut to compensate for wheel wear, a solenoidto actuate said compensator, a limit switch to actuate said solenoid,and means including a cam actuated by and in timed relation with therotary motion of said feed screw to actuate said limit switchautomatically to compensate for wheel wear.

2. In a grinding machine, as claimed in claim l, in combination with theparts and features therein specified of an electric counter actuated byand in timed relation with the transverse movement of the wheel slide,means including a limit switch actuated by and in timed relation withthe transverse movement of the wheel slide to actuate said counter, andoperative connections between said counter and said solenoid to actuatesaid compensator after a predetermined number of pieces of work havebeen ground to compensate for wheel wear.

3. In a grinding machine having a base, a rotatable work support, atransversely movable wheel slide, a rotatable grinding wheel thereon,means including a nut and screw mechanism to feed said slidetransversely in either direction, means including a motor to rotate saidscrew so as to impart a grinding feed to said slide, means including acontrol valve therefor, means including a manually operable switch toactuate said valve to initiate an infeeding movement of said slide, awork sizing gauge automatically to shift said valve to cause a rapidseparation of the grinding wheel and work when a work piece has beenground to a predetermined size, a feed compensator operatively connectedto impart a rotary motion to said feed nut to compensate for wheel wear,a solenoid to actuate said compensator, a limit switch to actuate saidsolenoid, and means including a cam actuated by and in timed relationwith the rotary motion of said feed screw to actuate said limit switchautomatically to compensate for wheel wear.

4. In a grinding machine having a base, a rotatable work supportthereon, a transversely movable wheel slide on said base, a rotatablegrinding wheel thereon, means including a nut and screw mechanism tofeed said slide transversely in either direction, means including amotor to rotate said screw so as to impart a grinding feed to saidslide, means including a control valve therefor, means including amanually operable switch to actuate said valve to initiate an infeedingmovement of said slide, a work sizing gauge automatically to shift saidvalve to cause a rapid separation of the grinding wheel and work when awork piece has been ground to a predetermined size, a grinding wheeltruing apparatus including a longitudinally traversable truing toolautomatically to true said grinding wheel after a predetermined numberof work pieces have been ground, a feed compensator operativelyconnected to impart a rotary motion to said feed nut to compensate forwheel wear, a solenoid to actuate said compensator, a limit switch toactuate said solenoid, and means including a cani actuated by and intimed relation with the rotary motion of said feed screw to actuate saidlimit switch unless the truing tool has worn away automatically tocompensate for truing tool and wheel wear.

5, ln a grinding machine having a base, a rotatable work support, atransversely movable wheel slide, a rotatable grinding wheel thereon,means including a nut and screw mechanism to feed said slidetransversely, means including a fluid motor to rotate said screw toimpart a grinding feed to said slide, means including a control valvetherefor, means including a switch to actuate said valve to initiate aninfeeding movement of said slide, a Work sizing gauge automatically toshift said valve to separate the grinding wheel and work when a workpiece has been ground to a predetermined size, an electric counteractuated by and in timed relation with the separation of the grindingwheel and work, a grinding wheel truing apparatus actuated by and intimed relation with said counter at count-out automatically to true saidgrinding wheel after a predetermined number of Work pieces have beenground, a feed compensator operatively connected to impart a rotarymotion to the feed nut, means including a limit switch operativelyconnected to actuate said feed compensator, and means including a camactuated in timed relation with a rotary motion of said feed screwnormally to actuate said limit switch unless the truing tool has wornaway so as to impart a compensating feeding to the grinding wheel tocompensate for wheel wear.

6. In a grinding machine having a base, a rotatable work support, atransversely movable wheel slide, a rotatable grinding wheel thereon,means including a nut and screw mechanism to feed said slidetransversely, means including a fluid motor to rotate said screw toirnpart a grinding feed to said slide, means including a control valvetherefor, means including a switch to actuate said valve to initiate aninfeeding movement to said slide, a Work sizing gauge automatically toshift said valve to separate the grinding wheel and work when a Workpiece has been ground to a predetermined size,

an electric counter actuated by the separation of the wheel andl work, agrinding wheel. truing apparz'xtus including a longitudinallytraversable truing tool automatically to true saidy grinding wheel' atcount-out after a predetermined number of work pieces have been ground,means to move said tool longitudinally through one completereciprocation, means automatically to feed said? tool transverselybefore each pass of the tool across the grinding wheel, a feedcompensator actuated by said counter at count-out, operative connectionsbetween said compensator and said feedl nut to'v impart a rotarycompensating adjustment tosaidfeed' nut, means including. a limit switchoperatively connected to actuate said feed compensato@ and meansincluding a. cam actuated in timed relation with the rotary motion: ofsaid feed, screw normally to actuate said limit switch unless the truingtoo-l has worn so as to impart a compensating feed to the grinding wheelafter a predetermined number of work pieces have. beenground tocompensate for wheel wear.

ReferencesCited in.y the file of this patent UNITEDL STATES PATENTS2,522,485 Silven et al. Sept. l2, 1950 2,582,610 Swainey Jan. 15, 19522,659,359 Hill Nov. 17, 1953 2,745,221 Comstock 3d u May 15, 1956

